package main

import (
	"encoding/json"
	"fmt"
)

type j struct {
	a int
	b int `json:BB`
	C int `json:CC`
	D int
}

func main()  {
	k := j{
		a: 0,
		b: 1,
		C: 2,
		D: 3,
	}
	a,_:=json.Marshal(k)
	fmt.Println(string(a))
}